Update pull-request.yaml

Adding rebase to pull-request actions

.github/workflows/pull-request.yaml

@@ -11,15 +11,20 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
 
       - name: Checkout into branch
         run: git checkout -b staging-pr-workflow
         
+      - name: Fetch main-source
+        run: git fetch origin main-source
+        
+      - name: Rebase to main-source
+        run: git rebase origin/main-source
+
       - name: Pull scripts
         run: sudo make pull-scripts
       
-      - name: Pull in all relevant branches
-        run: git fetch origin main
-      
       - name: Validate 
         run: sudo make validate